Littérature scientifique sur le sujet « Gc-Eag »

By means of GC, GC-MS and GC-combined EAG recordings (9Z,12E)-9,12-tetradecadien-1-ol (1) and (9Z,12E)-9,12-tetradecadienyl acetate (2) in a ratio of 4:1 were identified as the pheromone components of the female pyralid moth Euzophera punicaella M. originating from Armenia. Determination of EAG activity with male moth antennae and synthetic test chemicals revealed best responses with a mixture of both compounds.

Electrophysiological responses based on electroantennographic detection (GC-EAD) and electroantennography (EAG) analysis of Naupactus bipes beetles (Germar, 1824) (Coleoptera: Curculionidae: Brachycerinae) were used to test volatile oils of Piper gaudichaudianum, P. regnellii and P. hispidum. In the EAG experiments, female and male beetles showed significant EAG response to the three volatile oils of Piper species, with the females’ responses slightly higher than the males’. The experiments with GC-EAD revealed that some terpenoids (namely, α-pinene, β-pinene, myrcene, α-copaene and germacrene) present in the leaf essential oils of the Piper species are perceptible to female and male beetles.

Background A combination of gas chromatography-electroantennographic detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS) is typically used to screen active compounds that play a role in the regulation of insect behavior. This method uses two kinds of gas chromatography (GC) equipment and needs to compare compounds between the two chromatograms, and it is tedious and costly. To improve detection efficiency, as well as reduce costs and the rate of missed detection, we designed a system connecting gas chromatography (GC), electroantennography (EAG), and mass spectrometry (MS), with MS used instead of the flame ionization detector (FID) as the GC-EAD detector. To verify the feasibility of the improved method, we compare two methods—GC-EAG-MS and GC-EAD—through a series of experiments. Some researchers made similar improvements, but these were not compared with GC-EAD, and their method needed to be improved in the synchronization and split ratio. Our method has been optimized and improved in these aspects. Methods Helicoverpa armigera was the test organism; the improved method and conventional method were used to detect known and unknown compounds, as well as screen out active compounds that could generate responses in H. armigera antennae. Results Screening known single compounds using the two methods, the active compound benzaldehyde was detected in all seven concentrations of solution. By using the two methods, the five same active compounds of Helicoverpa armigera were detected in high concentration solution of the mixed compounds (100 mg L−1, 50 mg L−1); the four same active compounds were detected at 20 mg L−1 concentration; two identical same compounds were detected in low concentration solution (concentrations of 10 mg L−1 and below). By using the two methods, six identical active compounds of Helicoverpa armigera were detected in unknown compounds. Conclusion The improved method was consistent with the conventional method in terms of accuracy and sensitivity. However, compared with the traditional methods, Gas chromatography-electroantennographic-mass spectrometry (GC-EAG-MS) saved the cost of GC and FID equipment, thereby greatly lowering the experimental cost. In the experiment, GC-EAG-MS combined the two experimental operations of screening active substances by GC-EAD and identifying active substances by GC-MS into one, which not only reduced the experimental steps, but also avoided the false positive caused by the comparison of the two chromatograms, and it greatly reduced the difficulty level of the overall experimental analysis. GC-EAG-MS is more convenient, efficient, economical, and practical, and could confidently replace traditional methods. With further optimization, it could be widely applied in the study of plant and insect chemical ecology.

Abstract Tea black tussock moth, Dasychira baibarana (Matsumura) (Lepidoptera: Lymantriidae), is a devastating pest species of the tea plant in China. Here, we evaluated the responses of D. baibarana to tea plant volatiles using gas chromatography coupled electroantennographic detection (GC–EAD), eleclectroantennography (EAG), and a Y-tube olfactometer. In total, 11 of 18 analyzed compounds elicited GC–EAD responses from test insects. GC–EAD bio-active compounds were further investigated using EAG and behavioral responses. In the EAG analysis, male moths had significantly greater responses to four compounds [(Z)-3-hexenyl butyrate, (Z)-3-hexen-1-ol, ocimene and benzyl alcohol] than female moths. For females, maximum EAG amplitudes, were recorded in response to linalool, (Z)-3-hexenyl hexanoate and (Z)-jasmone. In EAG and behavioral bio-assays, the responses of both sexes were dose independent. In behavioral bio-assays male moths responding significantly to (Z)-3-hexen-1-ol, ocimene, (Z)-3-hexenyl butyrate, linalool, benzyl alcohol, and (Z)-jasmone at various concentrations. For females, significant behavioral responses were observed to (Z)-3-hexenyl hexanoate, followed by (Z)-jasmone, linalool, ocimene, and benzyl alcohol. However, neither sex was sensitive to 4 of the 11 tested compounds, phenyethyl alcohol, phenylacetonitrile, (E)-nerolidol, and indole. The present results showed that tea plant volatiles influenced the behavior of D. baibarana moths, which will greatly contribute in developing eco-friendly control strategies for D. baibarana, through the application of a blend of compounds that showed significant EAG and behavioral responses or a blend combined with female-produced sex pheromones.

The scent secretions of two subspecies of Hebomoia glaucippe, which are pierid butterflies, and the essential oils of their food plant were investigated by means of GC and GC-MS. The scent substances of either subspecies are found to be only E-β-ocimene, and the volatile components of Crataeva religiosa were identified as 2-hexanal, 3-hexen-1-ol, p-cymene, limonene, linalool, α-ionone, and β-ionone. Electroantennogram (EAG) were recorded with the antennae of adult male and female butterflies. It was found that EAG responses of male to E-β-ocimene were greater than those of females.

Abstract By means of electrophysiological investigations, GC- and GCMS-analysis of gland extracts and GC-analysis with EAG-detection (Z)-9-dodecenyl acetate was proven to be a component of the sex pheromone of female Cnephasia longana moths. (E)-9-dodecenyl acetate acts as a pheromone inhibitor, as shown by field trials.

Abstract By means of electroantennography and single cell recordings, GC and GCMS analyses and GC analysis with EAG detection (6E,11 Z)-6,11-hexadecadienal, (6E,11 Z)-6,11-hexadecadienyl acetate and (4E,9Z)-4,9-tetradecadienyl acetate were identified as the primary components of the sex pheromone of female Antheraea pernyi (Lepidoptera: Saturniidae).

European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is the most important pest of sweet and sour cherry fruit. This fly is difficult to control by insecticide application since most of the conventional insecticides used have been banned in Europe. Traps are used for both the pest’s mass trapping and the detection of the beginning of the flight period. Data on flies’ reactions to host-plant volatile organic compounds (VOCs) can be used to search for new attractants. VOCs were collected from the headspace of sour cherry, P. cerasus, fruit. Gas chromatography–mass spectrometry (GC–MS) resulted in the identification of 51 compounds. Terpenes and esters predominated in two aspects: in the highest diversity of the compounds, and the amount of the total VOC emissions (62.3%). Among the single VOCs, ethyl octanoate prevails, followed by (E)-4,8-dimethyl-1,3,7-nonatriene. GC–electroantennographic detection (GC–EAD) revealed 14 EAG-active compounds and those were identified. In Y-tube olfactometer tests, EAG-active compounds ((E)-β-ocimene, linalool, and (Z)-3-hexenyl 3-methylbutanoate) attracted R. cerasi females in a similar way to the odour of sour cherry fruit.

Electroantennography (EAG) is a simple, yet powerful technique that can be used to indicate that chemical compounds are detected by mosquito antennae. When coupled with gas chromatography (GC), it allows for the identification of detectable compounds within complex mixtures, including those in plant and animal headspaces that might influence mosquito behavior. EAGs and GC-EAGs reveal compounds that can be tested in behavioral assays with the goal of developing new repellents or attractants for mosquito control.

Les signaux olfactifs sont d’une importance cruciale pour la localisation d’hôte par les insectes, afin que ces derniers effectuent leurs besoins primaires nécessaires à leur survie et à celle de leurs progénitures. Les insectes s’orientent en détectant et discriminant les composés volatils émis par leurs hôtes via leurs organes olfactifs. La diversité d’information portée par les multiples composés volatils présents dans l’environnement contraint les insectes à utiliser des stratégies olfactives efficaces. Toutefois, ces stratégies demeurent peu connues pour les espèces à large gamme d’hôte comme les mouches des fruits Tephritidae. Cette famille d’insecte inclue des clades explorant diverses gammes d’hôtes, allant d’une gamme d’hôte plus large pour les espèces généralistes et une gamme d’hôte plus restreinte pour les espèces spécialistes. Ainsi cette thèse a comme objectif d’étudier comment les systèmes olfactifs des mouches des fruits se sont adaptés à la perception des fruits hôtes. Le travail effectué n’apporte pas seulement une connaissance fondamentale sur l’aspect évolutif de l’olfaction des insectes, mais sert également de guide pour la recherche d’attractifs pour plusieurs espèces d’insectes ravageurs. De plus, des développements de nouvelles méthodes en écologie chimique ont été réalisés au cours de cette thèse afin de mener à bien cette investigation. Cette thèse se concentre sur Bactrocera dorsalis, une espèce très compétitive et polyphage, et sur sept autres espèces de Tephritidae qui engendrent des impacts économiques importants sur les cultures fruitières et légumières dans les îles du sud-ouest de l’océan Indien. Les analyses des émissions volatiles de 28 espèces de fruits hôtes de mouches des fruits a permis d’identifier les contraintes évolutives associées à chaque composé des fruits. Nous avons mis en évidence l’existence de composés communs à plusieurs fruits et des composés spécifiques à une ou quelques espèces de fruits. Les analyses en électroantennographie triple (EAG3) et en chromatographie en phase gazeuse couplée à un détecteur d’électroanteannographie triple (GC-EAD3) effectué sur les différentes espèces de mouches des fruits mettent en exergue une corrélation négative entre les activités antennaires et la diversité des fruits émetteurs. Les tests comportementaux ont montré que Bactrocera dorsalis préfère les composés spécifiquement émis par quelques espèces de fruits aux composés communs entre les fruits lorsque ceux-ci sont présentés à faible concentration. L'hypothèse d’une adaptation à la polyphagie pour les espèces généralistes pourrait expliquer ces observations. Une perspective à cette étude est donc de tester le potentiel de piégeage d’un leurre combinant des composés communs de fruits avec quelques composés spécifiques afin d’augmenter la sensibilité olfactive et l’attractivité des mouches
Olfactory signals are of crucial importance for host localization by insects, in order for them to perform their primary needs for survival and that of their offspring. Insects navigate by detecting and discriminating volatile compounds emitted by their hosts via their olfactory organs. The diversity of information carried by the multiple volatile compounds present in the environment constrains insects to use efficient olfactory strategies. However, little is known about these strategies for species with a wide host range such as the Tephritidae fruit flies. This family of insects includes clades exploring various host ranges, ranging from a wider host range for generalist species to a narrower host range for specialist species. Thus, this thesis aims to study how the olfactory systems of fruit flies have adapted to the perception of host fruits. The work carried out not only provides fundamental knowledge on the evolutionary aspect of insect olfaction, but also serves as a guide for the search for attractants for several insect pest species. In order to carry out this investigation, new methods in chemical ecology were developed during this thesis. This thesis focuses on Bactrocera dorsalis, a highly competitive and polyphagous species, and seven other species of Tephritidae that cause significant economic impacts on fruit and vegetable crops in the southwestern Indian Ocean islands. Analyses of the volatile emissions of 28 fruit fly host species allowed us to identify the evolutionary constraints associated with each fruit compound. We highlighted the existence of compounds shared between several fruits and compounds specific to one or a few fruit species. The triple electroantennography (EAG3) and gas chromatography coupled to a triple electroantennography detector (GC-EAD3) analyses carried out on the different species of fruit flies highlighted a negative correlation between the antennal activities and the diversity of the emitting fruits. Behavioural bioassays showed that Bactrocera dorsalis prefers compounds specifically emitted by a few fruit species to compounds common to all fruits when presented at low concentration. The hypothesis of an adaptation to polyphagy for generalist species could explain these observations. A perspective to this study is therefore to test the trapping potential of a lure combining shared fruit compounds with a few specific compounds in order to increase the olfactory sensitivity and attractiveness of the flies